Research uncovers why zebras have stripes

Scientists from Royal Holloway, University of London and the University of Queensland have finally discovered the purpose of the zebra's black and white stripes.

According to the latest research zebras have bold patterns to conceal their movements and protect them from being attacked.

Although the zebra's black and white colour does not camouflage it against its background, scientists say that the stripes have a dazzling effect on predators.

Using computer models, researchers showed that the markings make optical illusions when the animals move, making it hard for predators to focus on individual animals.

"The stripes don't just confuse big predators like lions - pests and flies are affected too," says Professor Johannes Zanker from the Department of Psychology at Royal Holloway.

"The highly visible oriented stripes on a zebra's flank and the narrower vertical stripes on its back and neck give unexpected motion signals that confuse viewers, particularly in a herd of zebras. Our research suggests that these illusions cause pests and predators to mistake the zebra's movement direction, which would cause biting insects to abort their landing manoeuvres and chasing predators to mistime their attacks," he adds.

The functional significance of the zebra's stripe pattern is one of the oldest questions in evolutionary biology. "Zebra stripes have long confused scientists, right back to Darwin and Wallace," says Dr.Martin How, from the University of Queensland.

"Previous theories for the function of these stripes include social communication signals, camouflage at dusk or dawn in grassy habitats, and the so-called 'dazzle' effect when being pursued by predators or blood sucking insects," he added.